We propose to develop further ultramicro methods (sensitivity 10-12 mole) for the analysis of RNA and RNA derivatives and to apply such methods in detailed studies of the structure (sequences) of RNA, particularly transfer RNA, from normal and neoplastic mammalian cells, as well as from the murine sarcoma-leukemia virus, a RNA tumor virus. Methodology is to be designed in such a way that in vivo labeling with radioactive nucleic acid precursors will not be required. Such methods may then be applied to the analysis of RNA's from human tissues and of RNA species in general that are difficult to label homogeneously in vivo. The procedures will involve enzymatic and chemical degradation of RNA to oligonucleotides and nucleoside derivatives followed by chemical tritium incorporation into the fragments produced, chromatographic separation, and quantitative evaluation by liquid scintillation counting. We propose to apply such methods later in chemical studies on RNA, particularly tRNA, from various normal and neoplastic tissues, as well as from the murine sarcoma-leukemia virus. By studying a representative number of tumors of different etiology we hope to characterize differences between normal and neoplastic RNA in structural terms. Analyzing the structure of RNA in an RNA tumor virus and in host cells should define the relationship between viral and cellular RNA.